San Francisco seems to have done a good job of flattening the coronavirus curve. Initially perceived as an overreaction, the shelter-in-place order issued on 16 March now seems prudent in light of the sustained public health crisis that New York has endured.

San Francisco has seen roughly 1,450 confirmed coronavirus cases and 23 deaths but the city wasn’t always so good at heeding the advice of experts.

A century ago, the influenza pandemic hit San Francisco harder than any other major US city, with 45,000 infections and 3,000 deaths. As NPR’s Tim Mak pointed out in a 19 April Twitter thread, protests in late 1918 and early 1919 helped turn a manageable public-health situation into a disaster – courtesy of a now-forgotten movement known as the Anti-Mask League.

It began after the initial wave of infections in the fall of 1918 died down, the approximate juncture where California is now vis-a-vis Covid-19. But instead of flattening the curve, hostility to commonsense measures on grounds of personal liberty turned that curve into a double hump. Cases spiked in October, and mask use became mandatory, but only for four weeks. As of 21 November, they were no longer required.

Seemingly clear of danger, the city reopened, and a populace weary from the first world war and the widespread destruction of the 1906 earthquake and fire jumped back into the conviviality of life. Predictably, this led to a second wave of illness and death, and the city became convulsed by debates over the efficacy of masks and whether their use should be compulsory or not.

Then as now, a loose alliance of constitutional conservatives and economic boosters coalesced in opposition to the idea of masks, even as the caseload exploded to more than 600 a week by January 1919. A port city of 500,000 couldn’t seal itself off from the world the way a remote mountain town like Gunnison, Colorado, could, and ultimately around 3,000 residents would succumb to the flu. All the while, civic-minded physicians coaxed people into adopting masks as a kind of fashionable accessory, with one claiming that “chiffon veils for women and children have been as satisfactory as the common gauze masks”. But the Anti-Mask League complained bitterly that an obligation to cover one’s nose and mouth was an unconstitutional affront to the principles of a free society.

The San Francisco Board of Supervisors nonetheless reinstated the mask requirement on 17 January 1919. People caught without one were typically fined $5 or $10, money that was donated to the Red Cross, although a minority of scofflaws were sentenced to brief jail terms. In one case, a zealous public health official shot three people on a downtown street.

The League “seems to have been an ad hoc thing that was set up to respond to the board of supervisors reinstituting the mandate that citizens wear masks”, says Brian Dolan, a professor at the University of California San Francisco school of medicine. Local denim manufacturer Levi Strauss was a major producer of masks, Dolan adds, lending credence to the suspicion that profit was the real motive.

The medical literature was scant, with a Canadian health official casting doubt on masks’ effectiveness as well.

“He said it was quite clear from the epidemiological evidence: when people across the world were asked to wear masks, the numbers still went up,” Dolan says. “So people began to lose confidence against this measure, and his recommendation as a result was to focus on quarantine and isolation: what we’re calling social distancing.”

Protesters rally at the Capitol building in Sacramento on 20 April to demand that Governor Gavin Newsom ease coronavirus restrictions.Photograph: Rich Pedroncelli/Associated Press

Only a week after the supervisors took action, some 4,500 League members – far more than any gathering this month in Sacramento or Lansing – assembled at the long-gone Dreamland skating rink. After that show of force, the chair of the Anti-Mask League, one Mrs E C Harrington, implored the board of supervisors to grant “speedy relief” from the “burdensome” requirement. At least one supervisor rose to question the science behind masks as a preventive public health measure, claiming that unemployment among recently demobilized soldiers was a more urgent problem. Yet the city remained resolute, under the leadership of the health commissioner, Dr William C Hassler, the Dr Anthony Fauci of his day.

“Hassler and the mayor, whose wife was ill, called for remasking,” says historian John M Barry, a professor at Tulane University’s school of public health and the author of The Great Influenza. “But this time around, the outbreak was much less severe than in October and November and pushback was intense. Even the state board of health said masks were unnecessary. A bomb was even sent to Hassler – though it went to the wrong address, and no one was hurt. The business community and unions had both supported all control measures the first time around, and both opposed remasking.”

A person wears a protective mask while waiting for a bus in San Francisco.Photograph: Justin Sullivan/Getty Images

Parochialism and a wariness toward outsiders armed with expertise played roles very similar to today, says Bill Issel, professor emeritus of history at San Francisco State University. Social workers – often single, college-educated women – were met with “contemptuous criticism” in working-class neighborhoods. But what compounded that phenomenon in San Francisco was a widespread perception of municipal incompetence.

“The protests back in 1918 and 1919 were organized. That sort of distrust of experts, distrust of the government’s point of view was very strong,” Issel says. “The San Francisco of 1870 to 1920 was only gradually moving away from a city that had a huge problem raising enough money through bond issues and taxation to put sidewalks in the street.”

In other words, it was a question of the legitimacy of state power, underscored by the discomfort of citizens who could not see one another’s faces. Publicly concealing oneself has always been associated with lawlessness and behaviors deemed antisocial or deviant, from the bandannas worn by train robbers to the Guy Fawkes masks found on antifa street protesters to the beaked plague doctor costume found at masquerades and Edwardian balls.

While ordinary PPE isn’t nearly as grotesque, it’s still fraught. Even though New York’s Governor Andrew Cuomo has made public mask use mandatory, the state’s penal code still considers the wearing of a disguise on the street to be a form of loitering. In San Francisco today, enforcement of the mask requirement falls to restaurateurs and small-business owners who are already under serious financial strain. Chastising would-be patrons for violating a public health ordinance doesn’t create an atmosphere of hospitality, it’s true. But hopefully San Francisco learned its lesson from the last pandemic.